Cube ice separator and screening apparatus

ABSTRACT

A cube ice separator and screening machine for subdividing plural cube ice segments of connected cubes into disconnected individual cubes and separating smaller size fine pieces of ice therefrom, including an upwardly inclined conveyor screw and housing for feeding the ice along an upwardly inclined feed path. A network of rods forms an open ended cylindrical cage surrounding the conveyor screw along the upper portion of the feed path for breaking up the ice fragments into individual cubes and passage of the cubes through sized openings between the rods to a second conveyor station where the cubes and fine ice pieces are discharged along separate paths.

United States Patent [1 1 Morris, Jr.

CUBE ICE SEPAR ATOR AND SCREENING APPARATUS Inventor: William F. Morris, Jr., 801

' Fayetteville St., Raleigh, NC.

Filed: May 15, 1973 Appl. No.: 360,613 j References Cited UNITED STATES PATENTS 6/1971 Christianson 209/283 X 5/1966 Bakke 209/283 X 4/1973 Stevens 209/283 Jan. 29, 1974 Primary ExaminerAllen' N. Knowles Assistant Examiner-Gene A. Church Attorney, Agent, or Firm-Mason, Fenwick & Lawrence [57] ABSTRACT A cube ice separator and screening machine for subdividing plural cube ice segments of connected cubes into disconnected individual cubes and separating smaller size fine pieces of ice therefrom, including an upwardly inclined conveyor screw and housing for feeding the ice along an upwardly inclined feed path. A network of rods forms an open ended cylindrical cage surrounding the conveyor screw along the upper portion of the feed path for breaking up the ice fragments into individual cubes and passage of the cubes through sized openings between the rods to a second conveyor station where the cubes and fine ice pieces are discharged along separate paths.

16 Claims, 5 Drawing Figures PATENTEB JAN 2 9 F374 SHEU 1 0f 3 (N. N; M?

mm Q 2 PATENTED JAN 2 91374 SHEET 2 0F 3 MN F NN 1 CUBE ICE SEPARATOR AND SCREENING APPARATUS BACKGROUND AND OBJECTS OF THE INVENTION into individual ice cubes while advancing the ice along a path to a classifying station where smaller size pieces of ice are separated or screened from the ice cubes. Heretofore, automatic ice machines have been available which form large sheets of many interconnected ice cubes on approximately vertical mold surfaces of a band of evaporators. At the conclusion of the freezing cycle of the machine, when the'sheets of cube ice have been formed on the evaporator mold surfaces, the machine switches toa harvesting cycle wherein hot gaseous refrigerant is admitted to the evaporators to thaw the frost bond holding the ice sheets to the evaporators, allowing the icesheets to fall by gravity into a screw conveyor trough where the ice is transported to a discharge outlet. During the free fall of the ice sheets down rather narrow passages into the trough, impact of portions of the sheets on parts of the machine and impact of the lower portions of the sheets on the trough and on ice already in the trough causes the ice sheet to break up into random size segments of small numbers of ice cubes in each segment- Some of the ice breaks up into individual ice cubes while some of the segments mayinclude twelve or more, interconnected cubes.

Many of these segments of plural ice cubes are further broken up into smaller segments by impact of later falling ice on them, by crushing forces during travel of the ice along the conveyance path through the conveyor, and by impact with the conveyor screen flights. In any event, when the ice reaches the discharge outlet of the machine, it is a conglomerate of individual ice cubes, segments of the ice sheet having a plurality of interconnected cubes, and smaller size broken or crushed pieces of ice known as fines. Before collecting the ice into bags of ice cubes and bags of crushed ice or fines for commercial sale, the conglomerate ice discharge from the machine must be. farther re duced to individual cubes and the crushed ice or fines must be separated and conveyed along a separate processing path from the individual ice cubes.

An object of the present invention is the provision of a novel ice conveying device for receiving a conglomerate of plural cube segments of ice, individual ice cubes, and smaller size fines, conveying them along a path while breaking the segments into individual cubes, and separating the fines from the cubes.

Another object of the present invention is the provision of a novel ice conveying device as described in the preceding paragraph, wherein the ice is conveyed up an the accompanying drawings showing a preferred embodiment of the invention.

BRIEF DESCRIPTION OF THE FIGURES FIG. 1 is a side elevation view of the ice cube separator and screening machine in a cube ice processing line;

FIG. 2 is a top plan view of the ice cube separator and screening machine;

FIG. 3 is a fragmentary vertical longitudinal section view through the machine, taken along the line 3-3 of FIG. 4;

FIG. 4 is a transverse section view, taken along the line 44 of FIG. 1; and- FIG. 5 is a horizontal fragmentary section view, taken along the line 5-5 of FIG. 4.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT Referring to the drawings, wherein like reference characters designate corresponding parts throughout the several figures, there is illustrated in FIG. 1 an inclined ice cube conveying, separating and screening device indicated generally by the reference character 10 disposed in an automatic ice processing line to receive ice from a discharge conveyor I1 delivering ice, for example, from an ice storage bin or directly from the discharge conveyor line leading from an automatic ice making machine, the conveying, separating and screening device 10 being arranged adjacent a conventional ice bagging machine 12 to deliver cube ice to the bagging machine and being arranged to also deliver crushed ice or fines to a collecting station, indicated by the crushed ice receptacle 13 adjacent the bagging machine 12. The automatic ice making machine which provides the cube ice to be delivered to the conveying, separating and screening machine 10 is not shown, but may be of the construction illustrated and disclosed in my earlier patent application entitled CUBE ICE MAKING MACHINE AND METHOD, Ser. No. 303,037, filed Nov. 2, 1972 or may be of the general nature of the ice making machine which is the subject of FIGS. 7 to 9 of the C. E. Lowe U.S. Pat. No. 3,280,585 granted Oct. 25, 1966. Alternatively, automatic ice making apparatus of the type disclosed in Dedricks et al, U.S. Pat. No. 3,430,452 of Mar. 4, 1969 may be used to provide the cube ice.

The ice making apparatus is preferably of the type involving reversible cycle refrigeration wherein condensed liquid refrigerant is fed to a plurality of evapo- .rators or evaporator sections having vertical ice forming walls formed of a network or grid work of rectangular cube forming cells generally resembling a waffle iron with extremely thin divider partitions between the adjacent cells or receptacles. Water is discharged adjacent the top of these ice-forming surfaces to flow downwardly along the surfaces so that ice cubes are gradually formed in the cells during the freezing cycle. These ice cubes formed in the cells of each surface are typically connected together by relatively thin webs of ice at the outer edges of the divider partitions between the cells. At the conclusion of the freezing cycle, hot gaseous refrigerant is distributed to the evaporators or evaporator sections to thaw the ice bond holding the ice cubes to the surfaces of the cells so that the large sheet of connected ice cubes is released from the ice molding surfaces and is gravity discharged downwardly to a collecting bin, such as a screw conveyor trough or other collecting receptacle below the evaporator sections. During the thaw of these ice sheets from the ice forming surfaces, they usually strike against confronting surfaces of the ice making machine during their fall, breaking the sheets up into random sized sections of plural ice cubes, which are frequently further broken up as they impact against the ice already accumulating in the bottom of the trough or against surfaces of the trough. This conglomerate of individual ice cubes and broken sheet fragments of plural ice cubes is then conveyed along the conveyor path of the trough to the discharge outlet of the ice forming machine and may be then transferred by conveyors to ice storage bins or accumulating receptacles of various types or may be transported directly to the conveying, separating and screening machine 10. In any event, the ice in this conglomerate form reaches the conveying, separating and screening device by way of the discharge conveyor 11 which gravity discharges the ice received from either the ice forming machine or the ice storage bin into the inlet hopper 14 of the machine 10.

The machine comprises an elongated tubular lower section 15 of substantially U-shaped crosssection having a flat top 16 and a U-shaped trough portion 17 forming the side and bottom walls thereof, extending for a length of about 5- feet, defining a screw conveyor trough along approximately the lower half of the machine. The upper end of the lower conveyor trough portion 15 connectes to a separator and screen portion 18 which is about 5 feet in axial lengthand comprises a rectangular cross-section upper portion, as illustrated in FIG. 4, having a top wall 19 and side walls 20 housing a cylindrical elongated cage 21 formed of a network of spaced longitudinal and transverse rods and radial end rods, indicated generally at 22, as more specifically described hereinafter. The cylindrical cage 21 forms a continuation of the screw conveyor trough portion 15 and an elongated plural turn conveyor screw 23, for example of 9 inches diameter, extends through the entire length of the lower trough section 15 and the separator and screen section 18. The conveyor screw includes the customary elongated center shaft 24, for example of about 1% inch diameter, having its ends journaled in bearings 25 and 26 at' the upper and lower ends of the machine, and having the helical or spiral vane 27 welded or otherwise joined to the shaft 24 and extending substantially the full length of the machine. The lower end of the shaft 24 projecting below the lower bearing 26 and wall 28 at the bottom of conveyor trough section 15 is coupled by a shrouded pulley and belt drive 29 to the drive motor 30 to drive the conveyor screw at a speed of for example about 154 RPM.

The cage 21 formed of the rods 22 includes straight stringer rods 22A which are preferably spaced equal distances apart circumferentially about the cylindrical path defined by the rods and are in parallelism with the axis of the conveyor screw shaft 24, and are welded to the inside edges of outwardly surrounding transverse circular rings 22B formed of similar rods, each of which rod may be about 9% inch diameter stainless steel rods. The rods 22B forming the transverse rings in one example, may be spaced with their center lines about 2-% inches apart with the rings having an 1 1 inch inner diameter, so that the longitudinal stringer rods 22A will also be spaced just slightly over two inches apart. At the downstream or upper most end of the rod cage 21,

end rods 22C are welded to the ends of the longitudinal stringer rods 22A and extend inwardly along radial paths about 33% inches to provide a radial rod network against which the ice can be worked at the uppermost end of the cage.

Below the cage formation 21 and spanning the full length of the separator and screen assembly section 18 is a substantially U-shaped depending trough formation 31 formed of sheet material similar to that forming the sides 20 and top 19 of the section 18, having a helical conveyor screw 32 extending the length thereof,.for example of about 6-% inches diameter for transporting the small pieces or fragments of ice, generally referred to as fines to the fines discharged outlet 33. The fines discharge outlet 33 generally resembles a grating formed of parallel, circumferentially spaced rods 34, such as /& inch diameter stainless steel rods spaced apart 1 inch on centers to provide inch openings therebetween for gravitational passage of the fines through the spaces between the rods 34 into the fine chute 35 which covers the discharge outlet 33 and has, for example, a short cylindrical discharge spout 36 of about seven inches diameter to facilitate bagging of the fines.

The opposite ends of the shaft 37 of the fines conveyor screw 32 are journaled in bearings 38 and 39, the upper end of the shaft 37 which projects through the bearing 39 being coupled by a chain and sprocket drive 40 with the corresponding end of the upper conveyor screw shaft 24.

A cube ice discharge opening 41 is provided in the wall forming the depending trough 31 adjacent the upper end thereof for discharge of the cubed ice through a transition chute, if desired, as indicated at 42, into the supply hopper 43 of a conventional bagging machine 12 to facilitate collecting of the cube ice into bags of proper size formed from the supply roll 12A in a known manner.

The operation of the cube ice elevating, separating and screening machine should be apparent from an understanding of the foregoing description of the construction. The conglomerate of individual ice cubes, plural cube segments of broken ice, and some fine pieces of ice smaller than the ice cubes, is delivered from the source, whether it be an ice storage bin or an ice making machine, by the discharge conveyor 11 to the inlet hopper 14 of the machine 10. This conglomerate of ice is elevated by the rotating conveyor screw 23 along an upwardly inclined path through the lower conveyor trough section 15 and into the cage portion 21 formed of the stainless steel rods 22, where the inner action of the helical vane 27 on the plural cube ice fragments and the parallel stringer rods 22A lying inwardly of the transverse ring rods 22B breaks the plural cube fragments of ice into single cubes which, along with the fines which are of smaller sizethan the single cubes will primarily pass through the spaces between the rods 22A and 22B into the lower conveyor trough section 31 to be elevated by conveyor 32 toward the discharge opening 41. The fines then pass through the k inch wide spaces between the parallel rod 34 covering the fines discharged outlet 33 and into the fines chute 35 for discharge through the outlet opening 36 into appropriate bags. The ice cubes pass on upwardly over the rod covered fines discharge outlet 33 to the discharge opening 41 and fall into the inlet hopper 43 of the bagging machine 12. The plural ice cube fragments in the cage network which reach the upper end of the cage are forced against the radial end rods 22C, which with inner action of the conveyor screw finally succeeds in breaking up the more resistant fragments into individual ice cubes which then pass between the rods into the lower section for discharge through the cube opening 41. This machine therefore providesv for automatic breaking up of the ice delivered from the ice making machine or storage bin into individual separated cubes appropriate for bagging, in a manner permitting high speed production of bagged ice for commercial sale. This particular machine design achieves highly efficient breaking of the ice into cubes with minimum production of fines, producing for example about 95 percent ice cubes with less than 5 percent of fines. The machine can be operated in a working space which is maintained at subfreezing temperatures so as to avoid any melting of the ice during its processing from the ice making machine or from the storage bin to bagged cube ice.

What is claimed is:

1. Apparatus for processing ice in the form of a random ice mixture of broken plural cube segments of connected ice cubes of selected cube size, individual ice cubes, and smaller size fine ice fragments to subdivide the plural cube segments into individual disconnected ice cubes and screen the ice to withdraw the fine ice fragments and the ice cubes along separable discharge paths, the apparatus comprising housing means defining an upper ice segment subdividing zone extending along an ice feed path axis and a lower screening zone below said subdividing zone, a network of plural rigid rods defining an elongated cage formation in said subdividing zone including transverse rods extending transversely of said feed path axis spaced apart a distance slightly greater than said cube size and longitudinal rods paralleling said feed path axis spaced a similar distance apart and located immediately inwardly of said transverse rods, the cage extending substantially the length of said subdividing zone to form a separating member between said zones and having openings between the rods sized to pass individual ice cubes therethrough into the screening zone while restraining the larger segments in the subdividing zone, conveyor means for continuously feeding the ice mixture along said feed path axis in impacting relation to the cage rods for breaking the ice segments into disconnected ice cubes and gravity discharge of such cubes through the cage openings, and said screening zone including means for separating fine ice fragments therein from individual cubes and discharging the fine fragments and cubes along separate paths.

2. Apparatus for processing ice as defined in claim 1, wherein said cage formation is in the shape of an elongated cylinder concentric with said feed path axis havrotatable about said axis to convey the ice mixture into impacting relation with the cage rods.

4. Apparatus for processing ice as defined in claim 2, wherein said conveyor means is a conveyor screw extending into said cylindrical cage concentric with and rotatable about said axis to convey the ice mixture into impacting relation with the cage rods.

5. Apparatus for processing ice as defined in claim 1, including an inlet hopper, an elongated substantially cylindrical conveyor shell concentric with said feed path axis extending between said hopper and said subdividing zone for feeding the ice mixture to said cage formation and said conveyor means comprising an elongated continuous rotatable screw extending through the axial length of both said conveyor shell and said feed path axis in said subdividing zone.

6'. Apparatus for processing ice as defined in claim 2, including an inlet hopper, an elongated substantially cylindrical conveyor 'shell concentric with said feed path axis extending between said hopper and said subdividing zone for feeding the ice mixture to said cage formation, said shell defining a cylindrical conveyor tunnel adjoining the open end of said cylindrical cage formation in axial alinement therewith, and said conveyor screw extending through the axial length of both said conveyor shell and said cage.

7. Apparatus for processing ice as defined in claim 3, including an inlet hopper, an elongated substantially cylindrical conveyor shell concentric with said feed path axis extending between said hopper and said subdividing zone for feeding the ice mixture to said cage formation, and said conveyor means comprising an elongated continuous rotatable screw extending through the axial length of both said conveyor shell and said feed path axis in said subdividing zone.

8. Apparatus for processing ice as defined in claim 4,

including an inlet hopper, an elongated substantially cylindrical conveyor shell concentric with said feed path axis extending between said hopper and said subdividing zone for feeding the ice mixture to said cage formation, said shell defining a cylindrical conveyor tunnel adjoining the open end of said cylindrical cage formation in axial alinement therewith, and said conveyor screw extending through the axial length of both said conveyor shell and said cage.

9. Apparatus for processing ice as defined in claim 5, wherein said conveyor shell and conveyor screw extend along an upwardly inclined axis to concurrently elevate the ice while conveying it to and through said cage in said subdividing zone.

10. Apparatus for processing ice as defined in claim 6, wherein said conveyor shell and conveyor screw extend along an upwardly inclined axis to concurrently elevate the ice while conveying it to and through said cage in said subdividing zone.

11. Apparatus for processing ice as defined in claim 1, wherein said screening zone is elongated along a second path axially paralleling said feed path axis substantially coextensive with said cage formation, said screening zone having means defining a cube ice outlet and a fine ice outlet, means for conveying ice received through the cage openings along a second path toward said outlet for discharge therethrough, and fine ice passage means bounding a portion of said second path for passing fine ice gravitationally from said second path to said fine ice outlet.

12. Apparatus for processing ice as defined in claim 2, wherein said screening zone is elongated along a second path axially paralleling said feed path axis substantially coextensive with said cage formation, said screening zone having means defining a cube ice outlet and a fine ice outlet, means for conveying ice received through the cage openings along a second path toward said outlet for discharge therethrough, and fine ice passage means bounding a portion of said second path for passing fine ice gravitationally from said second path to said fine ice outlet.

13. Apparatus for processing ice as defined in claim 4, wherein said screening zone is elongated along a second path axially paralleling said feed path axis substantially coextensive with said cage formation, said screening zone having means defining a cube ice outlet and a fine ice outlet, means for conveying ice received through the cage openings along a second path toward said outlet for discharge therethrough, and fine ice passage means bounding a portion of said second path for passing fine ice gravitationally from said second path to said fine ice outlet.

14. Apparatus for processing ice as defined in claim 10, wherein said screening zone is elongated along a second path axially paralleling said feed path axis substantially coextensive with said cage formation, said screening zone having means defining a cube ice outlet and a fine ice outlet, means for conveying ice received through the cage openings along a second path toward said outlet for discharge therethrough, and fine ice passage means bounding a portion of said second path for passing fine ice gravitationally from said second path to said fine ice outlet.

15. Apparatus for processing ice as defined in claim 1, wherein said means for conveying in said screening zone is a rotatable conveyor screw rotatable about the axis of said second path and said fine ice passage means comprises a grating formation of parallel elongated rods spanning an opening in concentric parallelism with said last-mentioned axis and spaced to pass the fine ice therebetween.

16. Apparatus for processing ice as defined in claim 13, wherein said means for conveying in said screening zone is a rotatable conveyor screw rotatable about the axis of said second path and said fine ice passage means comprises a grating formation of parallel elongated rods spanning an opening in concentric parallelism with said last-mentioned axis and spaced to pass the fine ice therebetween. 

1. Apparatus for processing ice in the form of a random ice mixture of broken plural cube segments of connected ice cubes of selected cube size, individual ice cubes, and smaller size fine ice fragments to subdivide the plural cube segments into individual disconnected ice cubes and screen the ice to withdraw the fine ice fragments and the ice cubes along separable discharge paths, the apparatus comprising housing means defining an upper ice segment subdividing zone extending along an ice feed path axis and a lower screening zone below said subdividing zone, a network of plural rigid rods defining an elongated cage formation in said subdividing zone including transverse rods extending transversely of said feed path axis spaced apart a distance slightly greater than said cube size and longitudinal rods paralleling said feed path axis spaced a similar distance apart and located immediately inwardly of said transverse rods, the cage extending substantially the length of said subdividing zone to form a separating member between said zones and having openings between the rods sized to pass individual ice cubes therethrough into the screening zone while restraining the larger segments in the subdividing zone, conveyor means for continuously feeding the ice mixture along said feed path axis in impacting relation to the cage rods for breaking the ice segments into disconnected ice cubes and gravity discharge of such cubes through the cage openings, and said screening zone including means for separating fine ice fragments therein from individual cubes and discharging the fine fragments and cubes along separate paths.
 2. Apparatus for processing ice as defined in claim 1, wherein said cage formation is in the shape of an elongated cylinder concentric with said feed path axis having an open end through which the ice mixture is conveyed into the cage, said transverse rods being rings concentric with said axis located in parallel planes and said longitudinal rods paralleling the axis of the cylinder.
 3. Apparatus for processing ice as defined in claim 1, wherein said conveyor means is a conveyor screw extending into said subdividing zone concentric with and rotatable about said axis to convey the ice mixture into impacting relation with the cage rods.
 4. Apparatus for processing ice as defined in claim 2, wherein said conveyor means is a conveyor screw extending into said cylindrical cage concentric with and rotatable about said axis to convey the ice mixture into impacting relation with the cage rods.
 5. Apparatus for processing ice as defined in claim 1, including an inlet hopper, an elongated substantially cylindrical conveyor shell concentric with said feed path axis extending between said hopper and said subdividing zone for feeding the ice mixture to said cage formation and said conveyor means comprising an elongated continuous rotatable screw extending through the axial length of both said conveyor shell and said feed path axis in said subdividing zone.
 6. Apparatus for processing ice as defined in claim 2, including an inlet hopper, an elongated substantially cylindrical conveyor shell concentric with said feed path axis extending between said hopper and said subdividing zone for feeding the ice mixture to said cage formation, said shell defining a cylindrical conveyor tunnel adjoining the open end of said cylindrical cage formation in axial alinement therewith, and said conveyor screw extending through the axial length of both said conveyor shell and said cage.
 7. Apparatus for processing ice as defined in claim 3, including an inlet hopper, an elongated substantially cylindrical conveyor shell concentric with said feed path axis extending between said hopper and said subdividing zone for feeding the ice mixture to said cage formation, and said conveyor means comprising an elongated continuous rotatable screw extending through the axial length of both said conveyor shell and said feed path axis in said subdividing zone.
 8. Apparatus for processing ice as defined in claim 4, including an inlet hopper, an elongated substantially cylindrical conveyor shell concentric with said feed path axis extending between said hopper and said subdividing zone for feeding the ice mixture to said cage formation, said shell defining a cylindrical conveyor tunnel adjoining the open end of said cylindrical cage formation in axial alinement therewith, and said conveyor screw extending through the axial length of both said conveyor shell and said cage.
 9. Apparatus for processing ice as defined in claim 5, wherein said conveyor shell and conveyor screw extend along an upwardly inclined axis to concurrently elevate the ice while conveying it to and through said cage in said subdividing zone.
 10. Apparatus for processing ice as defined in claim 6, wherein said conveyor shell and conveyor screw extend along an upwardly inclined axis to concurrently elevate the ice while conveying it to and through said cage in said subdividing zone.
 11. Apparatus for processing ice as defined in claim 1, wherein said screening zone is elongated along a second path axially paralleling said feed path axis substantially coextensive with said cage formation, said screening zone having means defining a cube ice outlet and a fine ice outlet, means for conveying ice received through the cage openings along a second path toward said outlet for discharge therethrough, and fine ice passage means bounding a portion of said second path for passing fine ice gravitationally from said second path to said fine ice outlet.
 12. Apparatus for processing ice as defined in claim 2, wherein said screening zone is elongated along a second path axially paralleling said feed path axis substantially coextensive with said cage formation, said screening zone having means defining a cube ice outlet and a fine ice outlet, means for conveying ice received through the cage openings along a second path toward said outlet for discharge therethrough, and fine ice passage means bounding a portion of said second path for passing fine ice gravitationally from said second path to said fine ice outlet.
 13. Apparatus for processing ice as defined in claim 4, wherein said screening zone is elongated along a second path axially paralleling said feed path axis substantially coextensive with said cage formation, said screening zone having means defining a cube ice outlet and a fine ice outlet, means for conveying ice received through the cage openings along a second path toward said outlet for discharge therethrough, and fine ice passage means bounding a portion of said second path for passing fine ice gravitationally from said second path to said fine ice outlet.
 14. Apparatus for processing ice as defined in claim 10, wherein said screening zone is elongated along a second path axially paralleling said feed path axis substantially coextensive with said cage formation, said screening zone having means defining a cube ice outlet and a fine ice outlet, means for conveying ice received through the cage openings along a second path toward said outlet for discharge therethrough, and fine ice passage means bounding a portion of said second path for passing fine ice gravitationally from said second path to said fine ice outlet.
 15. Apparatus for processing ice as defined in claim 1, wherein said means for conveying in said screening zone is a rotatable conveyor screw rotatable about the axis of said second path and said fine ice passage means comprises a grating formation of parallel elongated rods spanning an opening in concentric parallelism with said last-mentioned axis and spaced to pass the fine ice therebetween.
 16. Apparatus for processing ice as defined in claim 13, wherein said means for conveying in said screening zone is a rotatable conveyor screw rotatable about the axis of said second path and said fine ice passage means comprises a grating formation of parallel elongated rods spanning an opening in concentric parallelism with said last-mentioneD axis and spaced to pass the fine ice therebetween. 